I was able to figure this out with the help of zoom support via chat. Similar to your case, my recipients weren't receiving any emails when I set a meeting invite, up until I finish setting up the Calendar and Contacts Integration - already a feature with my subscription so didn't have to pay any extra fee. Not sure if you have set that up already or not, I'll post the link and step below for anyone else to give it a shot.
You may follow this to set up calendar and contacts integration:
- Sign in to the Zoom web portal.
- Click Profile.
- Under Others, in the Calendar and Contact Integration section, click Configure Calendar and Contacts Service.
- Select a service.
- Change the permissions for the service.
- Click Next.
- Follow the on-screen instructions to grant Zoom access to the calendar/contacts service.
- After allowing access, you will be redirected back to the Zoom web portal, which will indicate the permissions for the calendar and contacts integration.
You can refer to this article for more information: https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0068615
Hope that helps.